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Last year, levels of methane in the atmosphere increased by the largest proportions since measurements began forty years ago. This situation is very worrying, because if methane is less abundant in the atmosphere than carbon dioxide, its short-term effects on the greenhouse effect are more powerful. Large amounts of methane are released by oil and gas drilling and pipeline leaks. Other sources are livestock, landfills and decaying organic matter in wetlands.
Methane is a greenhouse gas that has contributed regarding 0.5°C to global warming, according to the latest assessment by the Intergovernmental Panel on Climate Change (IPCC). Each molecule of methane added to the atmosphere causes an effect regarding 26 times greater on the greenhouse effect than a molecule of CO2, but it only stays in the atmosphere for regarding 10 years.
Atmospheric methane concentrations have been rising steadily for the past 15 years, and in 2021 saw a record rise from the previous year, reaching a new high, according to preliminary analysis by the National Oceanic. and Atmospheric Administration (NOAA). The previous record for the annual increase in methane levels was in 2020.
Due to the sharp increase in methane emissions in recent years, the role of this gas in accelerating climate change is gaining more and more attention.
Carbon dioxide is still a much larger contributor to global warming, and NOAA analysis released Thursday indicates that carbon dioxide levels have continued to rise rapidly in 2021. Over the past decade, carbon dioxide concentrations carbon emissions have increased at the fastest rate since monitoring began more than six decades ago.
The energy sector is responsible for regarding a third of global methane emissions
However, since the amount of methane contributing to global warming is greater over a shorter period, scientists view reducing these emissions as a faster way to curb warming. And, unlike carbon dioxide, which is released into the atmosphere when fossil fuels are burned for energy, methane is the main component of natural gas, meaning polluters have economic reasons not to. not let leaks release too much into the air. According to scientists, the energy sector is responsible for regarding a third of global methane emissions.
Besides trapping heat on the Earth’s surface, methane also contributes to ozone pollution, which can cause breathing difficulties and other health problems. According to NOAA estimates, methane is now more than two and a half times more abundant in the atmosphere than before the industrial revolution.
One factor that may have contributed to the rapid growth in methane emissions over the past two years might be increased rainfall in tropical regions, due to the weather phenomenon known as La Niña. The extra rain and humidity may have led to increased methane production by microbes living in tropical wetlands. These microbes are also more active when the weather is warmer, so natural methane emissions from wetlands might increase with global warming.
If we stopped emitting methane altogether today, methane-induced global warming would halve in regarding 20 years
At the World Climate Summit in Glasgow last year, more than 100 countries joined forces and pledged to cut global methane emissions by 30% by 2030. Countries that signed the agreement represent two-thirds of the global economy, but half of the 30 largest methane emitters, including Brazil, China, India and Russia, had not yet signed at the time of the report writing.
How can methane reduction be so much more effective than CO2 reduction, if methane contributes less to global warming? Because methane remains present in the atmosphere for a much shorter period than CO2. And, therefore, reducing emissions can reduce quite quickly the amount of this gas that is already present in the atmosphere. A visible difference in just a few decades.
Methane has a half-life of regarding ten years. Basically, if you emit 10 tons of methane today, 5 tons will still be present in the atmosphere ten years later. If we completely stopped emitting methane today, global warming caused by methane would halve in regarding 20 years. The contrast is striking with the CO2which has “lived” in the climate system for so long that, even without additional emissions, global warming induced by CO2 will last for centuries. This is why the slow progress in reducing CO2 is so detrimental: every ton of CO2 that we emit affects our climate system for hundreds, if not thousands of years, and continues to warm the planet.
A reduction in methane emissions is a quick win in terms of limiting global warming to a few tenths of a degree. However, this temperature drop is proportional to the rate at which methane emissions are reduced. So when the reductions stop (for example, if we stabilize global methane emissions at 30% below 2020 levels), the methane-induced warming will stabilize and then slowly start to rise once more.
Indeed, while the atmosphere reacts relatively quickly (a few years) to variations in the levels of greenhouse gases, the oceans, which also absorb these gases, react much more slowly. The entire climate system would take hundreds of years to return to equilibrium, so if we “freeze” the composition of the atmosphere, temperatures would continue to slowly rise over centuries. If we might reduce methane emissions following 2030 at a rate of regarding 3-5% per decade, this would counteract the slow balancing process and ensure a stable level of methane-induced global warming.
